Upgrade's Goal is Extra Seconds of Quake Warning

by Robert Sanders

Six years ago the deadly Loma Prieta earthquake struck the Bay Area
without warning, collapsing freeways, damaging the Bay Bridge and igniting San
Francisco's Marina district.

Now, thanks to a grant from Pacific Bell's CalREN program, Berkeley's
Seismographic Station is upgrading its seismic network to bring closer the time
when Northern and Central California will have critical early warning of quakes
like that.

In the case of distant quakes such as Loma Prieta, which struck near Santa
Cruz Oct. 17, 1989, strong ground shaking can take from 30 seconds to more than
a minute to reach the Bay Area. Early warning would give authorities a brief
period in which to respond.

"If you could get 20 to 30 seconds advance warning of a dangerous shock, you
could stop potentially hazardous equipment, like electrical generators," says
Berkeley seismologist Lind Gee. "With 30 seconds to a minute warning you can
begin to think about human response issues, like evacuation."

The $85,000 CalREN grant will subsidize installation of high-capacity
communication lines linking outlying earthquake detectors with the campus, and
linking the campus with the U.S. Geological Survey in Menlo Park.

Six of a planned 21 lines have been installed so far, and one detector is
already connected to the Seismographic Station to feed seismic data day and
night.

Gee estimates that with the new high capacity lines funneling "real-time" data
from detectors directly into the station, their computers eventually will be
able to analyze and spit out a preliminary magnitude and location within
seconds of a quake.

Seismographic Station director Barbara Romanowicz, professor of geophysics,
cautions that an early warning system would be of limited use to cities near
the epicenter of a quake.

"Most of the quake sources are in the Bay Area, so warning would be short,"
she says.

Cities farther from the epicenter could benefit, though. San Jose and Santa
Cruz, for example, could be warned of quakes at the north end of San Francisco
Bay, and vice versa.

Already the Seismographic Station has developed a program called REDI, for
Rapid Earthquake Data Integration, that alerts emergency preparedness agencies,
power and telephone companies and transportation agencies of an earthquake as
quickly as possible--typically within six to nine minutes of a temblor.
Operated in cooperation with the USGS, REDI delivers information via pager
after analysis at Berkeley and is made available to the public through the
World Wide Web at http://www.seismo.berkeley. edu/seismo/Homepage.html.

Berkeley, Lawrence Livermore National Laboratory and the USGS are now working
on an improved system that would provide warning within seconds.

"We are now at the point of developing equipment to see if it's feasible," Gee
says.

Essential to this goal is quick, reliable transmission of data from the field.
In Southern California the networks operated by the California Institute of
Technology and the USGS were set up with high capacity lines earlier this year,
thanks to a $98,000 grant from CalREN.

Berkeley's network, however, currently relies on old fashioned phone lines,
plus a few microwave relays and radio links, to get the information to
Berkeley.

These links can fail and block transmission of critical data, or can introduce
noise or glitches.

"The new network will provide more reliable and cleaner data," Gee says.
"Glitches can be mistaken for even big earthquakes, and now a lot of our
analysis time is spent trying to tell the difference between glitches and real
signals."

The system has the ability to route information around damaged parts of the
phone network, ensuring reliable, real time delivery. The system also can
transmit 56,000 bits of information per second.

An even faster link will be built between Berkeley and the USGS to carry 1.5
million bits of data per second, allowing the Seismographic Station and the
USGS to share earthquake data.

The high speed communication lines will also help seismologists collect other
types of geophysical data, such as position information needed to track earth
movement. The Seismographic Station operates a network of continuously
recording GPS (global positioning system) receivers in northern California to
monitor fault movement in cooperation with the USGS.

"Now we dial up once a day to get the data," Romanowicz says.

"With a continual connection we could do real time geodetic processing,
providing complementary information to the seismological data."

Berkeley also has nearly completed an expensive program to improve its 21
seismic detectors.

Soon each will have both a state-of-the-art strong motion detector designed to
record accurately during even the most violent shaking, plus detectors tuned
for sensitive monitoring of smaller quakes.

The USGS also has plans to upgrade its seismic network in the near future.

"The USGS network is denser, providing a more accurate and rapid position for
a quake, but with the dynamic range and accuracy of our instruments we can make
a more robust estimate of a quake's magnitude and rupture characteristics,"
Romanowicz says.

"In that sense our networks are complementary."

CalREN (California Research and Education Network) is a $25 million program
set up by Pacific Bell in 1993 to stimulate practical applications for emerging
communications technologies.